Anterior intervertebral interbody fusion is a common technique for treating degenerative disc disease and major deformity. The anterior approach is common for both the cervical (ACIF) and lumbar (ALIF) spine. The approach allows full visibility of the disc and fusion site, while minimizing disruptions to the branch nerves of the spinal column as well as major trauma to the posterior musculature. Typical intervertebral fusion consists of an interbody spacer and a fixation means, such as anterior plate or posterior pedicle screws. An objective of the interbody spacer is to maintain the height of the intervertebral space, but allow for bone to grow through the interbody spacer to form a fused mass between vertebrae.
Typically the interbody spacers are constructed from inert biocompatible material such as titanium or polyether-ether-ketone (PEEK). Titanium is typically used in orthopedic systems due to its strength and osteoconductive properties. However, in intervertebral spacers, titanium is not the preferred choice due to its high stiffness compared with bone. The large stiffness differential between bone and titanium has caused a high incidence of subsidence of the implant into the vertebral body. This has led the way for other biomaterials being selected for the spacer's body material. PEEK is a common interbody material selected because the Young's Modulus is extremely similar to bone and the material is extremely inert. However, PEEK is not an osteoconductive material and a large central oval cavity is the only space designed for bone through growth, thus the spacers remove a larger percentage of the fusion area.
Current orthopedic systems used to treat conditions in the anterior spine have started to incorporate plate fixation directly to the interbody (see, for example, US2009/0182430). These systems typically utilize specifically designed plates to interbody connections and do not give a large amount of flexibility in the operating room for the end user to interoperatively switch between a standalone interbody and an isolated interbody. In addition, the interbodies used in the standalone assemblies are constructed of the same inert material and do not allow for bone ingrowth to occur. The lack of fusion area increases the strength of the fixation required to maintain the construct rigidity during healing.
In July 2012, the United States (US) Food and Drug Administration (FDA) announced it was in the process of enacting rules to meet the congressional mandate for every medical device to contain a Unique Device Identification (UDI), such as lot number and part numbers. The US mandate requires every permanently implantable medical device to contain full traceability from manufacturer through distribution. This includes small devices that lack sufficient surface area to contain a distinguishable UDI. Typically, only sterile products have the ability to include a traceability sticker or manual lot recording is required for non-sterile products.